Protect Your Workers from Heat Stress

By Roy Maurer
6/13/2013

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The National Institute for Occupational Safety and Health (NIOSH) recommends that employers establish a heat-related-illness prevention program that includes advising workers to drink plenty of water and acclimatize to weather conditions and providing them with schedules that alternate between work and rest breaks.

NIOSH specifically extends this guidance to outdoor workers in agriculture, construction and other industries that expose workers to heat stress caused by great exertion and environmental heat, which can lead to severe illness or death.

Heat Stress Defined

Heat stress can be brought on by internal body heat generated by exertion (hard physical labor) and environmental heat arising from working conditions.

Contributing factors to heat stress include:

Moderate to high air temperature, particularly with high humidity.

Direct sun exposure.

Heavy clothing.

Lack of adequate water, rest periods and cooling-off conditions.

“Workers who are new to a worksite or returning from an absence of four or more days should gradually increase their workload and heat exposure over a week,” NIOSH recommends. “When a spike in temperature or a heat wave occurs, workers lose their acclimatization to the environment, and the risk of heat stress increases.”

The agency studied heat-related fatalities of workers in the United States from 1992 through 2006. During this period 423 worker deaths from environmental-heat exposure were reported. Of those who died, 102 were employed in the agriculture, forestry, fishing and hunting industries. Sixty-eight crop workers died from heat stroke, representing a rate nearly 20 times greater than for all U.S. civilian workers, NIOSH said. In 2011 the Department of Labor reported that 2 of every 1,000 workers are at risk for heat stress and that individuals in certain occupations—such as logging, firefighting, agriculture and construction—are at a greater-than-average risk.

Preventable Tragedies

According to the institute, in 2008 a 56-year-old male worker died of heat stroke after spending three days hand-harvesting ripe tobacco leaves on a North Carolina farm. On the third day the man started working at 6 a.m. He took a short midmorning break and a 90-minute lunch break. In midafternoon a supervisor observed the man working slowly and instructed him to rest, but the worker continued. An hour later, the man appeared confused, and co-workers carried him to the shade and tried to get him to drink water. He was taken by ambulance to a hospital, where his core temperature was recorded as 108 degrees, and, despite treatment, he died. On the day of the incident, the local temperature was approximately 93 degrees, with relative humidity of 44 percent. The heat index (a measurement of how hot it feels when both actual temperature and relative humidity are considered) was in the range of 86-112 degrees.

In another case, a 30-year-old male lawn landscaper collapsed and died of heat stroke in 2002. Two hours before his death he had complained of feeling light-headed and short of breath, but he refused his partner’s offer of assistance. The worker was on medication that had a warning about exposure to extreme heat, and this could have interfered with body-temperature regulation. The landscaper was pronounced dead at the hospital, with an internal temperature of 107.6 degrees. On the day of the incident, the maximum air temperature was 81 degrees.

What You Can Do

Prevention is the best way to avoid heat-related illness, according to NIOSH. The agency recommends that employers establish a heat-related-illness prevention program that includes the following measures:

Training for supervisors and workers to prevent, recognize and treat heat-related illness.

Implementing a heat-acclimatization program for workers.

Providing for and encouraging proper hydration.

Establishing work-rest schedules that are appropriate for heat-stress conditions.

Ensuring access to shade or cool areas.

Monitoring workers during hot conditions.

Providing prompt medical attention to workers who show signs of heat-related illness.

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